Hearing aid technology has progressed rapidly in recent years. Technology advancements in this field continue to improve the reception, wearing-comfort, life-span, and power efficiency of hearing aids. With these continual advances in performance of ear-worn acoustic devices, ever-increasing demands are placed upon improving the inherent performance of the miniature acoustic transducers that are utilized. There are several different hearing aid styles known in hearing aid industry: Behind-The-Ear (BTE), In-The-Ear or All-In-The-Ear (ITE), In-The-Canal (ITC), and Completely-In-The-Canal (CIC).
Generally, a listening device, such as a hearing aid, includes a microphone portion, an amplification portion, and a receiver portion. The microphone portion receives vibration energy, i.e. acoustic sound waves in audible frequencies, and generates an electronic signal representative of these sound waves. The amplification portion accepts the electronic signal, increases the electronic signal magnitude, and communicates the increased electronic signal (e.g. the processed signal) to the receiver portion. The receiver portion, in turn, converts the increased electronic signal into vibration energy for transmission to a user.
The electronic signal communicated from the microphone portion to the amplification portion, is susceptible to high frequency interference radiated, for example, in the range of 1-3 GHz. To reduce the sensitivity to low and high radio frequency interference (RFI), the conventional microphone assembly comprises a preamplifier assembly with capacitive coupling. In particular, the microphone portion can be communicatively coupled to the preamplifier assembly to reduce the RFI generated by communication devices such as cellular phones, web-enabled phones, personal digital assistants (PDAs), laptops, other devices that may be capable of communication over one or more public or private communication networks. Further, microphone assemblies include an external and an internal ground wirings or electrical paths to connect the portions of the microphone casing and further reduce the sensitivity to low and high RFI signals. However, known microphone assemblies provide poor RFI suppression in the presence of a communication device such as cellular phone and thereby making the microphone assembly less attractive to potential customers. In addition, known microphone assemblies that provide acceptable RFI suppression often require additional, and costly, assembly steps to connect and position ground wires between the individual external portions of the microphone casing.
The drawings are for illustrative purposes only and are not intended to be to scale.